“He who builds a mosque for Allah,

Mahmud ibn Labid reported: Uthman ibn Affan decided to rebuild the mosque (in Medina) but the people did not like this idea and they wished that it would be preserved in the same form. Therefore, Uthman said: I heard the Messenger of Allah, peace be upon him, say, “He who builds a mosque for Allah, then Allah will build for him (a house) like it in Paradise.”

[Sahih Muslim, Book 42, Number 7110]

عَنْ مَحْمُودِ بْنِ لَبِيدٍ أَنَّ عُثْمَانَ بْنَ عَفَّانَ أَرَادَ بِنَاءَ الْمَسْجِدِ فَكَرِهَ النَّاسُ ذَلِكَ وَأَحَبُّوا أَنْ يَدَعَهُ عَلَى هَيْئَتِهِ فَقَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ مَنْ بَنَى مَسْجِدًا لِلَّهِ بَنَى اللَّهُ لَهُ فِي الْجَنَّةِ مِثْلَهُ

صحيح مسلم كتاب الزهد والرقائق باب فضل بناء المساجد